Pharmaceutical compounds which enhance the transmission of serotonin (5-HT) are useful for the treatment of many psychiatric disorders, including depression and anxiety. The first generation of non-selective serotonin-affecting drugs operated through a variety of physiological functions which cause them to possess numerous undesired side effects, such as blurred vision, dry mouth, and sedation. The more recently introduced compounds, the selective serotonin reuptake inhibitors (SSRIs), act predominately by inhibiting 5-HT, which is released at the synapses, from being actively removed from the synaptic cleft via a presynaptic serotonin transport carrier. As SSRIs require several weeks before they exert their full therapeutic effect, this 5-HT blockade mechanism cannot fully account for their therapeutic activity. It is speculated that this two week induction which occurs before a full antidepressant effect is observed, is due to the involvement of the 5-HT1A autoreceptors which suppress the firing activity of the 5-HT neurons, causing a dampening of the therapeutic effect. Studies suggest that after several weeks of SSRI administration, a desensitization of the 5-HT autoreceptors occurs allowing a full antidepressant effect in most patients. Hence, it is believed that overriding this negative feedback by using 5-HT1A antagonists would potentially increase and accelerate the clinical antidepressant response. Recent studies by Artigas et al., Trends Neurosci., 19:378-383 (1996) suggest a combination of 5-HT1A activity and inhibition of 5-HT uptake within a single molecular entity can achieve a more robust and fast-acting antidepressant effect.
For example, U.S. Pat. No. 3,371,098 discloses sec. and tert. indolylethylamines useful as sedatives, anticonvulsants and analgesics.
U.S. Pat. No. 5,436,264 discloses N-aryloxyalkyl-tryptamine-like compounds of the following formula as alpha-1-adrenergic receptor antagonists for the treatment of cardiovascular disorders. ##STR2##
European Patent No. 0722 941 A2 discloses the preparation of a series of hetero-oxy alkanamines of the following formula for the treatment of depression and other conditions for which serotonin uptake inhibitors are used. ##STR3##
Japanese Patent Nos. 05255302 and 09040648 disclose the following compounds which are useful for the treatment of central nervous system-related diseases, such as anxiety and depression. ##STR4##